The objects of this invention are to increase the speed with which the display of an electrochromic display device may be electrically altered and to increase the visual contrast that may be obtained in such a device for a given expenditure of electrical power.
Electrochromic cells are known which comprise a sandwich arrangement of a layer of tungsten oxide (WO.sub.3) or other electrochromic material deposited on an electrically conducting substrate. The substrate serves as a first electrode, and it is usually, but not necessarily, optically transparent. The electrochromic layer is contacted by an electrolyte, which may be liquid, solid or semisolid. A second or counter electrode is in contact with the electrolyte. Such cells are, for example, disclosed in U.S. Pat. No. 3,708,220 to Meyers et al.